As a result of international agreements, it is now necessary in some industries and some geographies, and will become necessary world wide, to account for and pay for the emission of greenhouse gases. Mechanisms for accounting and payment may be required at all levels of commerce. Climate change resulting from greenhouse gas emissions has resulted in international agreements on limiting and reducing such emissions, e.g. the Kyoto agreement.
One method to limit emissions is through “cap and trade” practices. In this practice, entities that create emissions are required to purchase carbon offset certificates from entities that have earned such certificates by reducing, eliminating, or negating emissions. In general, emissions trading is done as a result of legal requirements while carbon offsets are purchased voluntarily. Today, on the European continent, carbon trades at about $30 per ton. In the future, if the United States agrees to limit its emissions, cap and trade is likely to become a requirement in the United States. In addition, with accelerated climate change, total limits or rationing of carbon may be imposed.
On-line shopping carts are ubiquitous. On-line shopping is often related to its physical counterpart. A user traverses a store, examines items, selects some to purchase, places the selected items in the shopping cart and checks out. Generally, these shopping carts are repositories for products that customers plan to purchase.